Device and method for integrating file systems

ABSTRACT

The present invention enables a user to increase storage capacity for a host by using multiple storage devices. File systems are virtualized regardless of any difference in file system format. The invention may be embodied as a device for integrating file systems or as a method of integrating file systems. The device has one or more storage device interfaces for storage devices, a host interface, and a hub connected to the interfaces. The hub creates a virtual file system that aggregates the storage device file systems of storage devices that are connected to the storage device interfaces. The method of integrating file systems includes reading file systems, interpreting them, creating a logical structure containing data of the file systems, and generating in a memory sectors that map the logical structure into a virtual file system.

BACKGROUND

Despite the increased storage capacities of newly developing storagedevices, such as the most recent versions of a USB flash drive, a user'sstorage needs will often exceed that which was once adequate. At thatpoint, the user wanting to increase storage capacity has variousoptions. One option is to obtain a new storage device with a greatercapacity, when such a storage device becomes available, and the userwill then have the task of transferring all existing stored data fromthe old storage device to the new storage device. The old storage devicethen becomes an unused resource.

Another option for a user wanting to increase storage capacity is toobtain additional storage devices and store data on the old and newdevices. The user then has to manage data that is stored on multiplestorage devices. The task can become burdensome as the user needs toaccess more and more file systems instead of one, which is the case whena single storage device has enough capacity for all the user's needs.

It would be desirable to be able to increase a host's storage capacityby using multiple storage devices and to be able to combine the devicecontents into a unified file system regardless of any difference in thefile system formats of the underlying storage devices.

SUMMARY

The present inventors have developed devices and methods for integratingfile systems, which enable a user to increase storage capacity for ahost by using multiple storage devices and virtualizing the devicecontents into a single file system regardless of any difference in thedevice file systems.

According to an example embodiment, a device for integrating filesystems includes one or more storage device interfaces, a hostinterface, and a hub. The storage device interfaces are for storagedevices, each of which has a storage device file system. The hub isoperationally connected to the storage device interfaces and to the hostinterface, and the hub is operative to create a virtual file system thataggregates the storage device file systems. The virtual file system mayaggregate the storage device file systems according to one or more firstconditions, at least one of which may be a host-level condition or afile-level condition. The hub may be further operative to distribute thecontents of a file received from the host interface to at least two ofthe storage devices and to represent the file in the virtual file systemas an undivided entity. Alternatively, the hub may be further operativeto route the contents of a file received from the host interface to onlyone of the storage devices according to one or more second conditions.

The device may have additional features. For example, at least one ofthe storage device interfaces may comply with the USB standard. Also,the host interface may be a wired interface, and the wired interface maycomply with the USB standard. The host interface may be a wirelessinterface. The hub may be further operative to create and maintainredundant file systems.

According to an example embodiment, a method of integrating file systemsincludes reading file systems of two or more storage devices,interpreting the file systems, creating a logical structure containingthe data in the interpreted file systems, and generating in a memorysectors that map the logical structure into a virtual file system. Thereading of the file systems may include communicating in compliance withthe USB standard. The logical structure may be created according to oneor more first conditions, at least one of which can be a host-levelcondition or a file-level condition. The method may include creating andmaintaining a redundant file system.

The method may further include representing a file in the virtual filesystem as an undivided entity, wherein the contents of the file aredistributed across two or more of the storage devices. Alternatively,the method may further include routing the contents of a file receivedfrom a host to only one of the storage devices according to one or moresecond conditions.

The method may further include representing the virtual file system to ahost through a wired interface, and the wired interface may comply withthe USB standard. Alternatively, the method may include representing thevirtual file system to a host through a wireless interface.

Example embodiments are described in detail below with reference to theaccompanying drawings, which are briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in the appended claims, which are readin view of the accompanying description including the followingdrawings, wherein:

FIG. 1 illustrates a system including a file system integrator inaccordance with a first example embodiment;

FIG. 2 illustrates a system including a file system integrator inaccordance with an alternate example embodiment; and

FIG. 3 illustrates a flow chart representing a method of integratingfile systems in accordance with an example embodiment.

DETAILED DESCRIPTION

The claims below will be better understood by referring to the presentdetailed description of example embodiments. This description is notintended to limit the scope of claims but instead to provide examples.Described first is an exemplary embodiment of a file system integrator.Described next is an alternate exemplary embodiment of a file systemintegrator. Also presented is a method of integrating file systems.

FIG. 1 illustrates, in accordance with an exemplary embodiment, a filesystem integrator 10 in combination with storage devices 12 a, 12 b, and12 c and a host 14. Non-limiting examples of storage devices in thissystem include USB flash drives, compact disks (CDs), and DVDs. The host14 shown in FIG. 1 is a personal computer, but other hosts that can befashioned to operate with the file system integrator include, e.g.,vehicle entertainment systems and DVD players. The file systemintegrator 10 enables a user to integrate file systems regardless of anydifferences in the individual file systems (e.g., in the file systemformats) of the attached storage devices.

The file system integrator 10 includes storage device interfaces 16 a,16 b, and i 6 c, a host interface 18, and a hub 20. The storage deviceinterfaces 16 a, 16 b, and 16 c connect the storage devices 12 a, 12 b,and 12 c, respectively, to the hub 20. Each of the storage devices 12 a,12 b, and 12 c has a storage device file system. The hub 20 is alsoconnected to the host interface 18. The hub 20 can be implemented ashardware, software, firmware, or any combination thereof. In thisexample embodiment, the hub 20 includes a controller 24, which has a RAM25. Although this example embodiment involves three storage devices andthree corresponding storage device interfaces, it will be understoodthat the number of storage devices and corresponding storage deviceinterfaces is not limited to this.

Upon connection of the storage devices 12 a, 12 b, and 12 c, acontroller 24 of the hub 20 creates a virtual file system thataggregates the individual storage device file systems. The virtual filesystem may operate to aggregate the storage device file systemsaccording to special conditions. Such operation can be useful insituations where system resources did not need to be used to aggregatethe information of files that would not be used by a particular host.For example, if the file system integrator 10 were intended for a hostthat is a DVD player, the file system could operate according to aspecial condition whereby the file system disregards during aggregationany information relating only to files that the DVD player could notread. The resulting virtual file system would represent to the DVDplayer only the files that it could read.

The hub 20 may store a file from the host 14 by distributing thecontents of the file to at least two of the storage devices 12 a, 12 b,and 12 c. The stored file would nonetheless be represented in thevirtual file system as an undivided entity. Distributing file contentsamong multiple storage devices is useful, for example, when none of thestorage devices 12 a, 12 b, and 12 c individually has enough free spacefor the file, but the total amount of unused space in the storagedevices collectively is enough.

The above example of aggregating only files in DVD format is an exampleof a host-level condition. The host may additionally or alternativelyaggregate files according to a file-level condition. For example, iffiles contents from a file sent by the host 14 were previouslydistributed across multiple storage devices, and one of those storagedevices were not presently connected to the host 14, the completecontents of the file would not be available to the host 14. The hub 20may then aggregate according to the file-level condition thatinformation relating to files in which the complete contents are notavailable is disregarded.

Alternatively, the hub 20 may be designed to route the contents of afile received from the host 14 to only one of the storage devices 12 a,12 b, and 12 c according to one or more special conditions. For example,a condition could be to route the contents of a file to only one ofstorage devices 12 a, 12 b and 12 c, if a particular one of the storagedevices has enough room for the file; such routing would save systemresources by eliminating spanning as unnecessary. Another examplecondition would be to route the contents of a file to a particularstorage device based on the file type; for instance, all DVD files wouldbe stored on the storage device 12 a, all audio files would be stored onthe storage device 12 b, and remaining files would be stored on thestorage device 12 c.

According to this example embodiment, the storage device interfaces 16a, 16 b, and 16 c comply with the USB standard. However, storage deviceinterfaces complying with other standards may be implemented instead orin addition.

Again, according to this example embodiment, the host interface 18complies with the USB standard, but alternate embodiments may usedifferent wired interfaces as the host interface. As a furtheralternative, the host interface could be a wireless interface.

The hub 20 may be designed to create and maintain redundant filesystems. An example of such a file system would be that of RAID(Redundant Arrays of Independent Disks) 1. RAID is an industry standardthat encompasses data storage schemes that divide and/or replicate dataamong multiple hard drives. A number of standard schemes have evolvedwhich are referred to as levels. The first level (designated as“RAID-1”) creates an exact copy (or mirror, or replica) of a set of dataon two or more disks in a way that is transparent to the host. Hub 20may also create and maintain redundant file systems using other waysknown to those of skill in the art.

Although the above example embodiment includes multiple storage deviceinterfaces 16 a, 16 b, and 16 c, the device may be implemented as a filesystem integrator 26 having only one interface 16, as shown in FIG. 2.The other elements of the file system integrator 26 are the same as inthe first example embodiment, as represented using the same referencenumbers. (Hub 20 of the file system integrator 26 also includes acontroller 24 and RAM 25, as shown in FIG. 1, even though forconvenience these elements have been omitted from FIG. 2.) Note alsothat as with the example embodiment represented in FIG. 1, although theexample embodiment of FIG. 2 involves only one storage device and onestorage device interface, the number of storage devices and storagedevice interfaces is not limited to such.

According to the embodiment shown in FIG. 2, the hub 20 still creates avirtual file system that aggregates individual storage device filesystems, even though the file system integrator 26 has only one storagedevice interface 16. The file system integrator 26 is able to accessmultiple storage devices 12 a, 12 b, and 12 c, and hence multiple filesystems, by a connection to the storage devices 12 a, 12 b, and 12 cthrough a multi-port hub 28, such as a USB hub, which connects thestorage device interface 16 using, e.g., a cable 30.

In other embodiments, the file system integrator 10 or 26 can be builtinto the outer casing of the host 14, with only the storage deviceinterface 16 or interfaces 16 a, 16 b and 16 c exposed. Alternatively,the file system integrator 10 or 26 can be joined to a general purposeinterface, such as a USB port, of the host 14 and the ports of themulti-port hub 28 or of interfaces 16 a, 16 b and 16 c can be placed ina convenient location for the user of the host 14.

Another example embodiment of the invention is a method of integratingfile systems, as represented by flow chart 32 in FIG. 3. This method maybe practiced using the file system integrator 10 of FIG. 1, the filesystem integrator 26 of FIG. 2, or alternate apparatus. The methodenables a user to integrate file systems regardless of any differencesin the individual file systems.

As shown in FIG. 3, the first step in the method is to read the filesystems of two or more storage devices. (Step S1.)

The next step is to interpret the file systems. (Step S2.) File systemsare interpreted by performing logical transformations of data based oninformation in the file systems and on other factors, such as the typeof host (for example, a DVD player or a personal computer), the identityof the user, or the presence of all parts of a spanned file. The data tobe transformed does not need to be limited to those of homogenous filesystems. Accordingly, file systems may be aggregated from storagedevices having differing file system formats.

After the file systems are interpreted, a logical structure is created.(Step S3.) Such a logical structure may be created, e.g., analogously tohow logical structures are created by using the “FORMAT” command inWindows® or by using the “mkfs” command in Linux, or in other ways knownto those of skill in the art. The logical structure created in step S3is then populated with the data in the interpreted file systems of stepS2.

Then, sectors are generated in a memory, such as in the RAM 25 in thecontroller 24 of hub 20 (FIG. 1). (Step S4). The sectors map the logicalstructure into a virtual file system as seen from a host. That is, thegenerated sectors contain the logical structure of the virtual filesystem as seen from the host.

Variations of this method are within the scope of the invention. Forexample, the reading of the file systems may be adapted to includecommunicating in compliance with the USB standard. The logical structuremay be created according to conditions, such as a host-level conditionor a file-level condition. The method may include creating andmaintaining a redundant file system.

The method may include the step of representing a file in the virtualfile system as an undivided entity such that the contents of the fileare distributed across two or more of the storage devices.Alternatively, the method may include the step of routing the contentsof a file received from a host to only one of the storage devicesaccording to specified conditions.

The method may include the step of representing the virtual file systemto a host through a wired interface, which may comply with the USBstandard. Alternatively, the method may include representing the virtualfile system to a host through a wireless interface, such as onecomplying with the Bluetooth or Wi-Fi standards.

Having thus described exemplary embodiments, it will be apparent thatvarious alterations, modifications, and improvements will readily occurto those skilled in the art. Alternations, modifications, andimprovements of the disclosed embodiments, though not expresslydescribed above, are nonetheless intended and implied to be withinspirit and scope of the claims. Accordingly, the foregoing discussion isintended to be illustrative only; the invention is limited and definedonly by the following claims and equivalents thereto.

1. A device for integrating file systems, the device comprising: aplurality of storage device interfaces including a first storage deviceinterface and a second storage device interface, each storage deviceinterface being operatively coupleable to a corresponding storage deviceof a plurality of storage devices, each storage device having acorresponding storage device file system; a host interface; and a hubconfigured for operatively connecting between the storage deviceinterfaces and the host interface, the hub operative to create a virtualfile system that aggregates the storage device file systems, wherein thevirtual file system is configured to: represent to a host, via the hostinterface, each file of a first group of files stored in one or more ofthe plurality of storage devices, wherein each file of the first groupsatisfies a first condition, and refrain from representing to the hosteach file of a second group of files, wherein each file of the secondgroup fails to satisfy the first condition, wherein the device isconfigured to distribute a first portion of a first file to a firststorage device via the first storage device interface and to distributea second portion of the first file to a second storage device via thesecond storage device interface and wherein in response to the secondstorage device being disconnected from the second storage deviceinterface, the virtual file system is configured to refrain fromrepresenting the first file to the host.
 2. The device of claim 1,wherein the first condition is satisfied by a particular file when theparticular file is readable by the host.
 3. The device of claim 2,wherein first condition is a host-level condition.
 4. The device ofclaim 2, wherein the first condition is a file-level condition.
 5. Thedevice of claim 1, wherein the hub is further operative to route thecontents of a particular file received from the host interface to onlyone of the storage devices according to a second condition.
 6. Thedevice of claim 1, wherein at least one of the storage device interfacescomplies with a universal serial bus (USB) standard.
 7. The device ofclaim 1, wherein the host interface is a wired interface.
 8. The deviceof claim 1, wherein the host interface is a wireless interface.
 9. Thedevice of claim 1, wherein the first condition is that for a particularfile, an entirety of the particular file is available to the host. 10.The device of claim 2, wherein the host is a digital versatile disc(DVD) player.
 11. The device of claim 5, wherein the second condition isthat the particular file is a digital versatile disc (DVD) file.
 12. Amethod of integrating file systems, the method comprising: distributingcontents of a first file among a plurality of storage devices, wherein afirst portion of the first file is distributed to a first storage devicevia a first storage device interface and a second portion of the firstfile is distributed to a second storage device via a second storagedevice interface, wherein the contents of the first file are representedin a virtual file system by an undivided entity; reading file systems ofthe plurality of storage devices; interpreting the file systems toinclude information relating to a first group of files, wherein eachfile of the first group of files satisfies a first condition, and todisregard information relating to a second group of files, wherein eachfile of the second group of files fails to satisfy the first condition;creating a logical structure that includes data stored in theinterpreted file systems; and generating sectors that map the logicalstructure into the virtual file system, wherein in response to thesecond storage device being disconnected from the second storage deviceinterface, the virtual file system is configured to refrain fromrepresenting the first file to a host.
 13. The method of claim 12,wherein the first condition is satisfied by a particular file when theparticular file is readable by the host coupled to a host interface. 14.The method of claim 12, wherein the first condition is a host-levelcondition.
 15. The method of claim 12, wherein the first condition is afile-level condition.
 16. The method of claim 12, further comprising:routing contents of a second file received from the host to only one ofthe storage devices according to a second condition.
 17. The method ofclaim 12, wherein reading the file systems includes communicating incompliance with a universal serial bus (USB) standard.
 18. The method ofclaim 12, further comprising representing the virtual file system to thehost through a wired interface, wherein the wired interface complieswith a universal serial bus (USB) standard.
 19. The method of claim 12,wherein the first condition is satisfied by a particular file when anentirety of the particular file is available to the host.
 20. The methodof claim 13, wherein the host is a digital versatile disc (DVD) player.